Electrical protective device.



L. N. (BRIGHTON.

ELECTRICAL PROTECTIVE DEVICE.

APPLICATION FILED mm 20, I916.

WITNESSES: INVENTOR Leslie M Crichton.

1 A.TTORNEY Patented Dec. 17, 1918.

LESLIE N. CRICI-ITON, 0F WILKINSBURG, PENNSYLVANIA, ASSIGNOR TO WESTING- HOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENN- SYLVANIA.

ELECTRICAL PROTECTIVE DEVICE.

Specification of Letters Patent.

Patented Dec. 47, 1918.

Application filed June 20, 1916. Serial No. 104,769.

To all whom it may concern:

Be it known that I, LESLIE N. Cniorrron, a citizen of the United States, and a resldent of Wilkinsburg, in the county of Allegheny My invention relates to electrical protective devices and particularly to relay mechanisms and systems that are employed for tripping circuit interrupters upon the 0c-v currence of predetermined conditions.

One object of my invention is to provide a simple and economical relay system of the character indicated that may be operated by current derived from the circuit, in connection with which the interrupter is employed, thereby obviating the necessity of employing a separate source of energy for supplying the operating currentfor its trip coil.

Another object'of my invention is to provide a system of the above indicated character that shall be adapted to control the tripping of a polyphase circuit interrupter with a single trip coil that receives energy from the circuit in connection with which the interrupter is employed.

Another object of my invention is to provide a system of the above indicated charactor that may be applied to circuit interrupters already constructed without the necessity of altering the structure of the interrupter or its trip coil.

A further object of my invention is to provide a system of the above indicated character that shall have means for connecting the trip coil in operative relation to the main circuit and for opening a short-circuiting connection that is normally connected between the terminals of the trip coil, under predetermined conditions.

Gopending application Serial No. 850,331, filed July 11, 1914, by B. H. Smith and assigned to the \Vestinghouse Electric and Manufacturing Company, discloses a tripping electromagnet that is adapted to be operated by the current derived from the circuit in connection with which its interrupter is employed. While a device of this type operates satisfactorily on mterrupters equipped therewith, it frequently becomes desirable to obtain the same result with 1nterruptcrs that are already constructed. In

view of this, I provide means whereby the electromagnetic device that is disclosed in the above mentioned application is adapted to normally short-circuit the trip coil of the interrupter and to disconnect the same from the circuit until the relay has so neutralized one of the windings of the electromagnetic device as to permit it to operate.

The single figure of the accompanying drawing is a diagrammatic view of a distributing system embodying my invention.

An alternatingcurrent three-phase circuit 1 is provided with a circuit interrupter 2 having a trip coil 3 that is adapted to be energized under predetermined conditions which are controlled by relays 4, 5 and 6 and electromagnetic devices 7, 8 and 9.

Three transformers 10, 11 and 12 are so associated with the conductors of the circuit 1 as to be traversed by current proportional to the current traversing the respective phases of the circuit 1. One terminal of each of the transformers is operatively connected to ground. The remaining terminals of the transformers 10, 11 and 12 are connected to the corresponding terminals of the windings 13, 14 and 15 of the relays 4, 5 and 6, respectively. The relays 4, 5 and 6 are preferably of the induction type and may be constructed as set forth in Patent No. 1,137,840 granted May 4, 1915, to the Westinghouse Electric and Manufacturing Company upon an application filed by Frank Conrad. However, to simplify the explanation of the operation of my invention, I have shown diagrammatically the relays 4, 5 and 6 that severally comprise a magnctizable core member 16, an armature 17 and movable and stationary contact members 18 and 19. The relays 4, 5 and 6 may be adapted to operate under any predetermined conditions and may be delayed or not in their time of operation.

The relays 4, 5 and 6 are adapted to control their respective electromagnetic devices 7. 8 and 9 which severally comprise oppositely disposed stationary core members 20 and 21 of U-shape and a movable core member 22 having an enlarged portion 23 that is disposed between the core members 20 and 21 and is normally in engagement with the core mcmber 21. A winding 24 is disposed around the movable core member 22 within the magnctizablc member 20. and two windtheir respective contact members 30 and 32.

ings 25 and 26 are disposed around the movable core member 22 within the magnetizable core member 21. The movable core member 22 is provided with an operating rod 27 having a. bridging contact member 28 and a spring 29 that supports a bridging contact member 29. The bridging contact member 28 is adapted to engage two movable contact members 30 and 31, and the bridging contact member 29 is adapted to engage two stationary contact members, 32 and 33. Under normal conditions, the contact members 30 and 32, and 31 and 33 are in engagement.

The terminals of the windings 13, 14 and 15 of the relays 4, 5 and 6, respectively, that are not connected to the transformers are connected to the terminals of the corresponding windings 24 of their respective electromagnetic devices. The windings 24 and 25 of each of the respective electroma netic devices are connected in series wit The contact member 31 of the device 7 is operatively connected, through a conductor 34, to the contact member 33 of the device 8, and the contact member 31 of the device 8 is connected through a conductor 35 to the contact member 33 of the device 9. The contact member 31 of the device 9 is connected to one terminal of the trip coil 3 and the other terminal of the trip coil is connected to the contact member 33 of the device 7. The contact members 32 of the several devices 7, 8 and 9 are operatively connected together and to ground through a conductor 36. Thus, under normal conditions, current proportional to the current that traverses the respective phases of the circuit 1 traverses the windings of the relays and the windings of their respective electromagnetic devices and no current traverses 'the trip coil 3 the terminals of which are normally short-circuited and disconnected from any source of electromotive'force.

The contact members 18 and 19 constitute the separable terminals of the windings 26 which are adapted, when close-circuited by the operation of the relays 4, 5 and 6, to so neutralize the effect of the windings 25 that the windings 24 predominate and cause the movable core members 22 to move upwardly. It will be understood that, under normal conditions, insuflicient current traverses the windings 13, 14 and 15 to actuate the armatures 17 and, since the magnetic circuits of the core members 21 are substantially closed, under these conditions, the windings 25 will predominate over the windings 24.

When an overload traverses the circuit 1, sufficient current will traverse the winding of the relay that is connected to the disturbed phase to cause it to operate in a time depending upon its time setting and to effect theoperation of its respective electromagnetic device. When the bridging members 28 and 29 engage the contact members 30 and 31, and 32 and 33, respectively, the trip coil 3 will be connected to the windings 24 and 25 and the corresponding transformer. Further movement of the movable core member 22 opens the short-circuit connection across the terminals of the trip coil 3 and permits current to traverse the same that is derived from the circuit in connection with which it is employed.

By the use of my invention, a polyphase circuit interrupter may be tripped by a single trip coil with current derived from the circuit in connection with which the interrupter is employed without changing the structure of either the circuit interrupter or its trip coil. Since the trip coil is normally disconnected from the transformer, there is no danger of effecting operation thereof on an excessive overload before the time-element relay operates.

I do not limit my invention to theparticular system or devices illustrated, as it may be variously modified within the'scope of the appended claims.

I claim as my invention:

1. In a polyphase electric circuit, the combination with a circuit interrupter, a single trip coil therefor that is normally disconnected from the circuit, a transformer connected to each phase of the circuit and a relay connected in series with each transformer, of an electromagnetic means connected in series with each relay and controlled by its respective relay for operatively connecting the trip. in circuit with one of the transformers after the relay operates.

2. In a polyphase electric circuit, the combination with a polyphase circuit interrupter, a single trip coil therefor that is normally disconnected from --the circuit, transformers operatively connected to the circuit, and relays connected in circuit with the corresponding transformers, of means connected in series with the'relays and controlled thereby for operatively connecting the single trip coil in circuit with one of the transformers, under predetermined conditions.

3. In a polyphase electric circuit, the combination with a circuit interrupter and a trip coil therefor that is normally sh0rtcircuited and disconnected from the circuit, of a plurality of transformers connected to the circuit, a plurality of time-element relays connected in circuit with the respective transformers, and means connected in circuit with the respective relays and controlled thereby for connecting the trip coil 4. In a polyphase electric circuit, the combination with a circuit interrupter, and a trip coil therefor that is normally shortcircuited and disconnected from the circuit, of a plurality of transformers connected to the circuit, a plurality of relays connected in circuit with the transformers, and means controlled by the relays and supplied with current from the circuit for connecting the trip coil in circuit with one of the transformers and its corresponding relay and for open-circuiting the normally maintained short-circuit connection across its terminals.

5. In a polyphase electric circuit, the combination with a circuit interrupter and a trip coil therefor that is normally short-circuited and disconnected from the circuit, of relays operatively connected to the respective phases, and means operatively connected in circuit with the relays and controlled thereby for connecting the trip coil in operative relation to the circuit only when the relays operate.

(3. In a polyphase electric circuit, the combination with a circuit interrupter and a trip coil therefor that is normally shortcircuited and disconnected from the circuit, of relays operatively connected to the re spective phases, and means operatively connected in circuit with the relays and controlled thereby for connecting the trip coil in operative relation to the circuit and for opening the short-circuit connection across its terminals only when the relays operate.

7. In a polyphase electric circuit, the combination with a circuit interrupter and a trip coil therefor that is normally short-circuited and disconnected from the circuit, of a relay for each phase, and means connected in series with the windings of the relays and controlled thereby for connecting the trip coil in series With the windings of the relays and for opening the short-circuit connection across its terminals, under predetermined conditions.

8. In a three-phase electric circuit, the combination with a circuit interrupter and a single trip coil therefor, of three series transformers connected to the respective phases of the circuit, three time-element relays connected in series with corresponding transformers, three electromagnetic devices connected in series with the corresponding relays and controlled thereby, and contact devices actuated by the electromagnetic devices for normally short-circuiting and disconnecting the trip coil from the circuit and for connecting the trip coil to the circuit and opening the short-circuit connection thereof only after one or more of the relays have operated.

9. In a polyphase electric circuit, the combination with a circuit interrupter and a single trip coil therefor, of a plurality of electromagnetic devices connected to the phases of the circuit foroperatively connecting the trip coil to the circuit, and timeelement relays connected in circuit with the electromagnetic devices for, so controlling the same that the trip coil is only connected to the circuit after the relays operate.

In testimony whereof, I have hereunto subscribed my name this 16th day of June LESLIE N. CRIOHTON. 

